With the evolution of semiconductor technology, especially the development of wearable electronic products, the demand for low power consumption of electronic products has become increasingly more important in recent years. A bandgap reference voltage source is a stable voltage supply source and is suitable for use in wearable electronic products if its power consumption can be reduced.
Bandgap reference voltage sources can be categorized into different types depending on power consumption and noise immunity. In general, a reduction in the power consumption of a bandgap reference voltage source also reduces its noise immunity. For example, current bandgap reference voltage sources can be categorized into 10 uA, 5 uA, and 1 uA types. The 10 uA bandgap reference voltage source has the highest noise immunity and consumes the highest power. The noise immunity of the 5 uA bandgap reference voltage source is lower than that of the 10 uA bandgap reference voltage source, accordingly, the 5 uA bandgap reference voltage source is not suitable for high-speed applications. The noise immunity of the 1 uA bandgap reference voltage source is the lowest, so that the 1 uA bandgap reference voltage source is only suitable for low-speed applications.
However, the power consumption of even the 1 uA bandgap reference voltage source is still too high to be suitable for wearable electronic products. One of the reasons is that the bandgap reference voltage source is in an always-on state. Thus, the current approach for improving the bandgap reference voltage source requires a trade-off between power consumption and noise immunity, or a combination of a low-power, noise-immunity bandgap reference voltage source and a high-power, high-immunity bandgap reference voltage source through system control to reduce the power consumption. However, this approach has the drawbacks of increasing the system operation complexity and the electronic circuit layout area.
Therefore, a novel bandgap reference voltage source and method of operating the same is needed to achieve high noise immunity at low power consumption.